Coding and decoding device utilizing a cathode ray type tube



May 19, 1959- l.. FRENKEL 2,887,612 `CODNG: AND DECODING DEVICE UTILIZING A CATHODE RAY TYPE TUBE Filed 0G11. 17. 1956 ATTORNEY 2,887,612 Patented May 19, 1959 United Sttes Pate t" CODING AND DECODING DEVICE UTILIZING A CATHODE RAY TYlE TUBE Lothar Frenkel, San Diego, Calif., assigner to General Dynamics Corporation, Rochester, N.Y., a corporation of Delaware Application October 17, 1956, Serial No.` 616,461

1 Claim. (Cl. S15- 21) This invention relates generally to a device utilizing a cathode ray type tube for coding or decoding of pulse code, such as a binary code.

Present day computing devices generally operate and respond to various types of pulse code, and generally utilize a common language, such as binary code. Tubes and systems such as are encompassed by the instant invention are well known and exemplified by, for instance, the patent to Albert M. Skellett, U.S. 2,710,361. The

instant invention improves on the prior art, such as ex-y emplified by Skellett, and materially simplies the construction and operation of a device including a cathode ray type tube capable of coding and decoding code such as binary code.

In the instant invention the electron beam of the ltube may be positioned at various desired locations or openings in and upon a perforated target. The graduated size of the openings controls the amount of beam current passing therethrough. for impingement upon the anode or main target. The device will keep the beam at the position or opening that has been selected in the perforated target by feeding back to the deiiection plates a portion of the generated output voltage. pulse will effect a voltage change in the plates which will, accordingly, move the beam from the illuminated target opening to the next target opening, and, so on, dependingl upon the number of pulses which are fed into they device. The perforted target may be so constructed that ten openings indicate a -9 count. Multiples Vof tenopenings or such other pluralitylof openings as may be 'desired can be employed. The'openings and the space to the adjoining opening being limited only by the beam width of the particular electron beam utilized to illuminate the openings. The openings themselves may be of any known geometric configuration. Their function being to pass a predetermined amount of beam current.

.lt is ian object of the present invention to provide a new and improved device for coding and decoding of codes, such as, binary code.

It is another object of the present invention to provide a relatively simple and trouble-free binary coding and decoding device.

it is another object of the invention to provide a binary coding and decoding device employing a cathode ray type tube having therein means to limit the current of the electron beam in proportion to the desired count established by the input pulses.

lt is another object of the present invention to provide a device which responds to pulse information to provide stepped voltage output.

It is another object of the present invention to provide a device which inherently is highly versatile in application in that a large number and combination of pulse counting can be achieved by selective design of the perforated target within the cathode ray type tube.

Other objects and advantages other than those set forth herein above will become apparent when read in combi- A subsequent input.

nation with the accompanying specification and drawings, 1 in which:

Figure 1 is a diagrammatic view partially in cross section ofthe device embodying the invention;

Figure 2 is an enlarged detailed view showing the perforated target utilized in the cathode ray type tube of Figure l.

Reverting to Figure 1, there is shown a cathode ray type tube 10. Tube 10 utilizes lan evacuated container 11 having positioned therein an electron gun 12 at one end thereof for the generation and projection of an electron beam 13 alongthe tube 10 .toward an anode or electron responsive target 14 at the other end of the tube. Electron beam 13 may have a predetermined current density. Intermediate the target `14- and the gun 12 beginning at the gun end of the tube 10 and looking toward the target 14, are positioned accelerating and focusing electrodes 17, such as are common to the cathode ray tube art, for projecting the electron beam 13 along the tube toward the target 14. A pair of deection plates 18, 19 for lselectively deecting the beam is placed ahead of the electrodes 17. Intermediate the deection plates 18, 19, and the anode 14 is placed a perforated target 20 having formed therethrough a plurality of graduated s sized perforations or openings 21 for selectively passing more or less current density of the electron beam 13. These openings 21 may be of any desired geometric configuration and may vbe aligned in any desired manner generally congruent with beam deflection.

Openings 21 are shown here alignedy in a plane generally yat right angles to that of the plane of inuence effected by the deflection plates upon the beam. Deiiectionl of the beam 13 by the deflection plates 18, 19 may effect a substantially lineal deiiection of the beam when the openings 21 are lineally aligned, thereby effecting a positioning of the cross section of the electron beam through the selected opening 21 in the perforated target 20. The selected opening will effect a limiting action upon the beam cross section thereby limiting the amount of beam current or cross sectional portion of the beam which passes through the opening 21 to the anode 14. 1t should be understood that the basic concept of the invention resides in varying beam current by use of the perforated target in substantial proportion with the count of the input pulse code, IP, to achieve a stepped voltage output, OP.

In operation, the beam 13, preferably as large or larger than the largest opening 21 through which it is to be projected, may be so aligned that the center of the beam coincides with the center of the opening 21. Beam current transmitted therethrough to the anode 14 will therefore be substantially proportional, in general, to the cross sectional area of the opening 21 illuminated. As the beam 13 comprises negative charges of electricity, it will be clear that impingement thereof on the anode 14 would effect a voltage, intermediate the points R11 and R21, of a value which is more negative than that point is normally biased to. The resulting more negative voltage Will be coupled to one plate 19 of the deflection plates 18, 19 through resistive element R4. The negative voltage appearing at the deection plate 19 will effect a repulsion of the electron beam from the plate 19 toward the opposite plate 18 and thereby move or hold the beam to the top side of the perforated target 14 (top, that is, as viewed in the drawings, wherein R4 appears on the bottom side of the drawing). The openings 21,

therefore, may be arranged in the perforated target in such a manner that each successive perforation to the top permits an additional portion of the beam to be transmitted therethrough.

As additional beam current is impinged on the target 14 the feedback to plate 19 will cause a further depression of potential over that which would obtain if the beam were centered upon any perforation to the bottom thereof. The value of successive more negative steps of potential may be varied bysuitable choice of R11 and R21, as well as, by varying the area of successive perforations 21 in the perforated target 14 `thereby varying, of course, the amount of current density of the electron beam 13 transmitted therethrough. It should, therefore, be clear that the invention is capable of varying the current value of the electron beam in response to input pulses. There is, therefore, shown in this invention sufcient means of control, namely R11 and R21 voltage coupled to plate 19 by resistor R4, to permit operation of the device so that the beam current transmitted through the perforation 21 will suice to depress the plate potential by an amount necessary to hold the beam in the last given position. It can be seen, therefore, that feedback of anode potential to plate 19 permits a stabilized position to be achieved at any desired perforation at which the beam is momentarily centered. This condition is maintained until a further pulse IP coupled by capacitor C to plate 19 drives the beam to a new position. Such new position will generally be the next adjacent perforation, the resulting potential of the new position is then fed back to the bottom deection plate 19 to hold the beam in the new position.

It should be understood then, that the beam may be shifted from one perforation to the next (or toward the top) by application of input pulse, IP, through capacitor C, of negative polarity to the plate 19. Therefore, if the pulse decays while the new steady-state establishes itself, the new state will maintain itself indefinitely or until the application of the next successive pulse. It is obvious, of course, that the application of a pulse of opposite polarity, namely, a positive input pulse will effect a shift of the beam to the bottom, therefore, performing a subtractive function rather than an additive function.

R1 and R2 furnish a predetermined Voltage, determined by their value and that of B+ across R3. R3, being adjustable, furnishes the voltage desired to be impressed on plate 18 to effect the desired initial positioning of beam 13.

It can, therefore, be seen that the device, including the tube, is capable of counting external pulses by responding to each new pulse (depending on its negative or positive polarity, it will either add or subtract, respectively) with a new potential step at an output OP from target 14.

Although but one embodiment has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without the parting from the spirit of the invention or from the scope of the appended claim.

I claim:

A device capable of coding and decoding pulse code input information including a cathode ray tube having positioned at one end thereof means for generating and projecting an electron beam, said beam having a predetermined beam cross section, a target positioned at the other end of said tube for rresponding to selectively part and all of said beam cross section, a pair of deflection plates positioned intermediate the generating means and the target for effecting selective decction of said electron beam, a perforated target positioned intermediate the deflection plates and the target, one of said pair of plates having impressed thereon a predetermined voltage, the other of said pair of plates being capacitively coupled and responding to said input information and being adapted with said one of said pair of plates to cause selective and sequential positioning of the beam upon the perforated target in response to the input information, said perforated target having substantially lineally aligned, graduated openings adapted to be sequentially selected, the openings being adapted to pass selectively part and all of said beam cross section in progressively greater or lesser sequentially positioned openings from the part to the all of said beam cross section of the beam according to the opening selected by said plates, said target being electron responsive to the part of said beam passed by the opening selected to produce an output voltage, a resistance element conductively connected with the one of said pair of plates and with said target, said resistance element coupling a proportionate part of said output voltage to the one of said plates for holding said beam at the opening then being illuminated, said input information being subsequently applied to said plates to cause said beam to be moved one step to either of the adjacent openings.

References Cited in the le of this patent UNITED STATES PATENTS 2,463,535 Hecht Mar. 8, 1949 2,591,981 Van Overbeek Apr. 8, 1952 2,668,927 Jonas Feb. 9, 1954 2,733,358 Carapellotti Jan. 31, 1956 

